1. Field of the Invention
This invention relates to a device for supporting a ribbon of glass, having at least one roller arranged in an area of an underside of the ribbon of glass.
2. Discussion of Related Art
A widely used method for producing flat glass is the float method. During this method, molten glass is poured on a bath of liquid tin, spreads on it and solidifies while being pulled out of a tin bath in an area of reduced temperatures. Fire-polished surfaces are created on the top and underside, in the process, which do not require further finishing.
The ribbon of glass is lifted off the surface of the bath at the cold end of the tin bath and is transported over a series of rollers to a cooling furnace, in which the glass is cooled to room temperature in a controlled manner and the tension is relieved during the process.
In a conventional manner, lifting the ribbon of glass off the tin bath is also performed by rollers. During the ongoing operation, these rollers are intended to lift the ribbon of glass gently off the tin bath, while the advancement force for the ribbon is provided by the rollers of the cooling furnace. However, at the start of production, or in case of an interruption which leads to the ribbon of glass being snapped off, the first rollers downstream of the tin bath have to provide this advancement force.
The first roller downstream of the tin bath in particular is subjected to relatively high temperatures, and soiling of this roller by particles from the tin bath dragged along is most extensive. Because of the high temperatures, some of these particles adhere to the surface of the roller, which results in damage to the underside of the newly formed ribbon of glass.
The replacement of the first rollers after shaping by an air cushion table is described for example in U.S. Pat. No. 3,615,315 and U.S. Pat. No. 4,081,260. Thus it is possible to prevent damage to the surface, because the ribbon of glass is guided over a surface without contacting it. However, one disadvantage of this method is that no drawing force can be exerted by this air cushion table.